Composite lens.



PATENTED OCT. 9, 1906.

" G. A. MAGBETH.

COMPOSITE LENS. APPLICATION FILED FEB. 26. A1906.

WITNESSES ZZ memon UNITE l earns Param? orricn.l

Application filed February 26, 1906. Serial No. 302,929.

To all whom it may concern.- l

Be it known that I, GEORGE A. MACBETH, a citizen of the United States, residing at Pittsburg, in the county of Allegheny and Stateof Penns lvania, have inventedcertain new and usefu Improvements in Composite Lenses, of which the following is a specification.

The invention relates toj lamp lenses, and has for its objects to rovide a powerful lens adapted to transmit fight freely through all ortions thereof of such construction that the interior of the lamp may be observed through the lens without distortion and by which means the condition of the flame may be conveniently noted from the front without the necessit of 'o venin the lamp; and to provide a ens o simp e and ineX ensive construction which when transmitting light will present a new and attractive appearance and one in which the full efficiency of the light may be utilized. One form of the invention is shown 4in the accompanying drawing, in

` which- Fi re l is-a side elevation of the lamp to whichu the lens is applied with the center thereof broken away to show a sectionv of the lens and the interior of the lamp, and

Fi re 2 is a front View of the lamp.

Inldnses of this general type it is of course desirable that the light. from the lamp be brought into some sort or other, and it has been customary to make them in a variety of shapes, as lane-convex, convex or concaveconvex wit corrugations, whereby the light may be refracted in the desired direction, but all of these lam s are open to the objection that after the am has been lighted and closed it is impossib e to jud e accurately the 'condition of the flame by ookingl into the lamp from the front, because of the distortion caused by the curvature and thickness of the glass. vMy lens has been designed to overcome this difficulty by providing a lens vin which a portion thereof is of such construction that it will not distort the light, and therefore by means of which the light may be accurately adjusted after the lamp is closed. It has lbeen the design to secure this result without in any way diminishing the efficiency of the lens.

As shownv in Vthe drawings, the lens is applied to a vehicle lam 3 of ordinary construction 1provided with the illuminating means 4 o any preferred construction, and

Specification of Letters Patent.

parallelism by means of a re-v fractmg lens o Patented Oct. 9, 1906.

backfaces 8 and 9 are parallel and constitute the band 10 as shown in Figure 2. This band constitutes a means whereby the flame may be observed from the front of the lamp without opening it. It will be apparent because of the opposite parallel sides 8 and 9 of the band that no distortion due to refraction will occur when looking throu h such band, and that the flame may therefore be accurately adjusted. rlhe annular band lf't'rill not of course bring into arallelism the ire`ct rays from the light as oes the corrugated center of the lamp, but such divergent rays are useful in broadening the field ofthe lamp, and

the reflected rays from the concave 'reflector i may be made to pass through such annulus f in approximate parallelism with rays throu h the corrugated center. When lightedv tie face of the lamp presents an attractive appearance, and it will besfurther observed that the full eiciency of the lamp is preserved, although the field is somewhat broadened by the divergence of the direct rays through the band 10. It will also be noted that'from a manufacturing stand oint the construction is advantageous in tlliat the thickness of the glass` from the edges to the center varies sli tly', obviating any strains in cooling whicli are -induced in a glass vof widely varying thickness, such as a lens with a band similar to 10, and a convex bulls-eye. The construction also results in saving of weight over the convex bulls-eye, and a better and more uniform transmission of light. Other advantages will be apparent to those familiar with the art.

Having thus described my invention and illustrated its use, what I claim as new, and l desire to secure by Letters Patent, is the following.' y

l. convex concave lens of substantially uniform thickness -throu hout and having ai uniformly curved front ace and a rear face having the same ygeneral curvature as the` through the annulus in parallelism while the direct Irays from the lamp pass therethrough in a diverging direction.

In testimony whereof I have hereunto 15 sigied my name in the presence of the tWo su scribed Witnesses.

GEO. M AOBETH.

Witnesses;

F. E. GAITHER, ARGHWORTH MARTIN. 

